1. Field of the Invention
The invention relates in general to guide rails, and more specifically to new and improved guide rail clamping methods and apparatus for attaching and accurately positioning elevator guide rails in a hatchway or hoistway of a building.
2. Description of the Prior Art
The movable elements of an elevator system, such as the elevator car and its counterweight, are guided throughout their respective travel paths in the hoistway of a building. The guiding system conventionally includes guide rails, which have a substantially T-shaped cross-sectional configuration, which rails are fixed in the hoistway, and guide elements, such as guide roller assemblies, with the guide elements being carried by the elevator car and counterweight. The guide elements coact with three guide surfaces on each of the guide rails to guide the movable elements.
When an elevator system is installed, extreme care must be taken to properly align the sections which make up each complete guide rail, to properly locate each group of aligned sections between the front and back walls of the hoistway, called the "fore-aft" axis, and to accurately space the two groups of aligned sections, called the "between guides" or B.G. axis.
The conventional T-shaped guide rail includes first and second flanges and a stem. The stem defines the three guide surfaces, one on the nose or face of the stem portion, and one on each side of the opposed surfaces of the stem.
The presently used methods and clamping apparatus for fastening elevator guide rails in hatches has been used for many years. A bracket, usually shaped like an angle, is fastened to the hatch wall or building steel. The guide rail is clamped to the bracket using clamps commonly called rail clips. These clips are of three basic types, a fixed clip, a sliding clip, and a pressed clip. The fixed clips are usually forged parts and are used for heavy-duty and/or low-rise installations. The forged clips exert high clamping forces on the rail. If the building settles, the rail will not slide through the clips. The sliding clips and pressed clips are used in higher rise buildings, to allow the rail to "slip" through the clips as the building settles, thus preventing the guide rails from distorting.
During installation of the guide rails, field personnel must "plumb" the guide rails and maintain the B.G. distance between rails within close tolerances. In order to accomplish this, the field personnel must leave the bolts, washers and nuts sufficiently loose to allow the rail to be moved on the fore-aft axis, and also loose enough to enable shims to be placed between the guide rail and rail bracket, in order to adjust and maintain the B.G. dimension. This "loose-hardware" condition is extremely difficult to work with since one axis adjustment affects the other. The rail clips sag and tend to skew on the rail. The pressed clips are mare of mild steel, and they derive their "spring" effect as a result of forming its final shape in a die. This "spring" effect is defeated if the pressed clip is mishandled while being clamped to the rail. If not held exactly in position, it will become permanently deformed. Thus, when the clips sag on the rail, it is common for them to be deformed when the bolts are tightened, and they will not firmly clamp the rail.
The "shimming" step uses special double-slotted shims placed over the hardware to maintain the proper center distance between the two rail clip bolts, which, in turn, assure that the clips remain in contact with the rail. Since guide rails are available in a plurality of different weights and dimensions, with the size of the rail being dictated by the specific application thereof, it is necessary to produce and maintain a large inventory of double-slotted shims, which are made of many thicknesses and center distances between slots to accommodate each size rail and each type of clip for each rail.
In addition to the field installation problems, the manufacture of pressed clips is both difficult and costly. Tooling maintenance is difficult and expensive.
The sliding clip, used primarily for high-rise duties, is constructed of brass, and is thus a very costly assembly to manufacture.